DE9311938U1 - Rolling bearings with a verifiable wear condition - Google Patents

Description

1
Rolling bearings with verifiable wear condition

The invention relates to rolling bearings, in particular directional rolling bearings, whose wear state can be checked.

A rolling bearing usually has two rings that can rotate relative to each other via rolling elements, such as rollers or balls, arranged in a rolling track provided between the two rings. This rolling track is usually filled with grease to limit the friction between the various elements of the rolling bearing.

Nevertheless, the rolling track wears out as the bearing is used. This can cause damage over time. One method for checking the state of wear of rolling bearings is to analyse the proportion of particles contained in the grease that are particularly caused by the wear of the rolling track.

Now, taking a grease sample can sometimes be quite inconvenient. This is especially true for so-called directional bearings, which are generally very large bearings (in the order of 1m to 6m in diameter), such as those mounted between the fixed and the moving chassis of a crane, for example, and which thus enable the crane to be aligned.

It is certainly not possible to dismantle such a rolling bearing in order to take a sample of grease. The only solution known to date is to take some of the grease that has leaked out of the seals that are arranged between the two rings and seal the bearing gap formed between them.

Apart from the fact that it can be quite difficult to get into the area of the seals, it is also clear that such a grease sample only provides information that is dated with a corresponding time delay.

In fact, depending on the type of bearings used, it can take between 6 months and 1 year for the used grease to pass from the rolling track to the seal. This is due to the distance and the tortuous path between the rolling elements and the seals, as well as to the various obstacles that must be overcome along the way. In addition, the extraction of grease at a given time only provides information on the state of wear of the bearing 6 months or 1 year before that time. Even if one were to inject clean grease again after this extraction to check the wear information, one would have to wait another 6 months to 1 year to confirm the results of the first extraction.

Another disadvantage of this method is that the grease sampled outside the seals may be contaminated by contaminants that do not come directly from the bearing. In this case, the analysis of the grease sample may be falsified and provide incorrect information about the condition of the bearing.

The invention is based on the object of providing a better solution to these problems.

The aim of the invention is to provide a rolling bearing that allows grease extraction that is easy to implement and provides information with a shorter time delay than current solutions.

Another aim of the invention is to provide a rolling bearing that allows a grease removal that is truly representative of the wear of the rolling bearing.

The subject matter of the invention is a rolling bearing, in particular a directional rolling bearing, with the features described in claim 1.

If the rolling bearing is a directional rolling bearing, it usually operates in certain predetermined alignment positions more often than in other positions. For this reason, the wear of the rolling bearing can be uneven. Therefore, the concentration of metal particles in the lubricating grease substance is not the same at all points around the circumference of the rolling track. An advantage of the invention is then that the lubricating grease substance can be removed at various selected points in the bearing gap.

A further embodiment of the invention is the subject of claim 3, where a rolling bearing, in particular a directional rolling bearing, is described with two rings, which can be rotated relative to one another by means of rolling elements arranged in a bearing gap provided between the two rings, which can contain a lubricating grease substance. A rolling bearing of this type has, according to the invention, at least one passage formed in one of the two rings and a hollow element which is removably inserted into this passage and has a front insertion opening which is located inside said passage at a predetermined distance from the end of this passage which opens into the bearing gap, wherein the hollow element can store part of the lubricating grease substance during the movement of the rolling elements.

In order to avoid a plug of dried grease clogging the passage, the distance mentioned is advantageously chosen to be smaller than or equal to the diameter of the passage.

In addition, the area of the ring in which the passage is formed is an area of minimal mechanical stress.

The hollow element is advantageously made of a non-metallic material, so that the further analysis is not distorted. In addition, according to one embodiment of the invention, it comprises a hollow tube which can receive the lubricating grease substance through the said frontal inlet opening and has a front wall at its other end which is connected to the outside of the hollow element via a narrow passage.

If the rolling bearing is a directional rolling bearing, it is particularly advantageous if it has several passages which are arranged in at least one of the two rings and which are associated with a corresponding number of hollow elements. They are distributed at selected points around the circumference of the ring or rings in question.

Further advantages and features of the invention emerge from the following detailed description of embodiments shown in the drawings.

Fig. 1 shows an axial partial section of a first embodiment of the rolling bearing according to the invention,

Fig. 2 shows a hollow element of a rolling bearing according to the invention,

Fig. 3 to 6 show axial partial sections of further embodiments of the rolling bearing according to the invention.

Fig. 1 shows a rolling bearing, designated as a whole by 1. It has an outer ring consisting of two parts 2 and 3, which in this example is screwed directly to the movable chassis of a crane, while the inner ring of the rolling bearing, designated by 4, is attached directly to the fixed chassis. The two rings, which are separated from one another by a bearing gap 5, form three rolling tracks 6, 7 and 8 in the present case. The upper axial rolling track 6 is intended for rolling elements 9, e.g. in the form of rollers, which are arranged on a cage 11. The lower axial rolling track 7 is intended for lower rolling elements 10, also in the form of rollers, which are arranged in a cage 10. The middle radial rolling track 8, located between the lower and upper rolling tracks, is also intended for rollers 13.

Lubrication holes (not shown in this figure for reasons of simplification) are arranged in a regular distribution around the circumference of the outer ring. They open into the bearing gap 5 and enable the introduction of a lubricating grease substance (also not shown for reasons of simplification) into this bearing gap. Upper and lower seals 14 and 15 respectively serve to keep the lubricating grease in the bearing gap.

Two passages 16 and 17 are formed in the outer ring, which open on the one hand into the outside of this ring and on the other hand into the bearing gap 5 at the level of the upper rolling track 6 or the lower rolling track 7. Each of these passages, e.g. passage 16, has a recess 18 with a diameter of, for example, 40 mm, which extends into a cylindrical bore. This has a part 19 provided with an internal thread, which is followed by a smooth part 20 that opens in the area of the rolling track.

The passages mentioned are arranged in areas of minimal mechanical stress so that they do not cause any weakening of the rolling bearing. In this context, it can be seen in the example shown that the two passages open at a sufficiently large distance from the two inner rounded areas 29 and 30 of the two parts of the outer ring 2, which represent zones of high stress.

In each of these openings a hollow element 21 is removably inserted, the

Structure is explained in more detail below with reference to Fig. 2.

The hollow element 21 comprises a hollow tube 23, which in the present example has an outer diameter of 15 mm and an inner diameter of 13 mm. It has an end opening 22 facing the rolling track and an end wall 26 on the opposite side. The tube 23 consists of an externally smooth part 25, which in the present example extends from the end opening 22 over a length of 61 mm, and an adjoining external thread part 24, which can cooperate with the internal thread part 19 of the passage in question.

The hollow element 21 ends in its end area opposite the opening 22 in a screw head 28, which can be supported in the recess 18 when the hollow element is screwed into the passage. This screw head enables the hollow element to be blocked in the threaded part. Another shape is also conceivable (e.g. a screw head with a slot, hexagon socket, etc.). In the middle of the head 28, between the end wall 26 of the hollow tube 23 and the free surface of the head 28, a narrow passage 27 with a diameter of, for example, 1 mm is formed. It connects the hollow tube 23 to the outside space. Its function is explained in more detail below.

The length of the hollow tube is here approximately 81 mm, while the length of the bore 19, 20 of the passage is slightly greater. Therefore, the end opening 22 of the hollow tube is at a distance D from the end 23 of the passage 16 which opens into the bearing gap of the rolling bearing when the hollow element 21 is inserted into the opening 16. In general, it is particularly advantageous if this distance D is smaller than or equal to the inner diameter of the bore 20 of the opening 16. The reasons for this are explained below.

When the rolling bearing is assembled on site, the bearing gap is filled with grease through lubrication holes. The movement of the rolling elements 9, 10 and 13 causes the used grease to penetrate into the interior of each hollow tube 23. The presence of the narrow passage 27 makes it possible for the air pocket that forms on the bottom of the hollow tube to be evacuated and thus does not create a counterpressure in the tube 23 that would prevent the grease from penetrating into the interior of this tube. When, after a certain period of time, which is usually less than 6 months, the hollow element 21 is filled with grease, the hollow element 21 is unscrewed in order to remove it from the ring in question. The hollow tube filled with grease is sent to the laboratory for analysis. A new one is immediately

Pipe inserted.

Since the time required to fill the hollow tube with grease is clearly shorter than the time required for the same grease to penetrate from the rolling elements into the space outside the seals, the information available after analysis of the grease is dated with a shorter time delay. In addition, if an anomaly is detected, it is easy to take a new sample within a shorter time period in order to confirm the information obtained from the previous sampling.

Although the invention also reveals its full advantages when using a hollow tube that opens directly into the bearing gap, it has been observed that it is particularly advantageous to choose the distance D to be smaller than or equal to the diameter of the opening, i.e. the outside diameter of the hollow tube. By such a dimensioning, the formation of a plug of dried lubricating grease that would otherwise develop over time can be avoided, which would be deposited along the wall of the bore 20 between the end 23 and the opening 22 of the hollow tube.

It is also readily apparent to the person skilled in the art that taking the grease directly at the level of the bearing gap, and in particular as close as possible to the rolling elements, enables the analysis of grease contaminated exclusively by the metal particles actually resulting from the wear of the rolling tracks.

In order to avoid falsification of the analysis, it is further advantageous if the hollow element 21 is made of a non-metallic material, e.g. of a plastic, such as polyamide.

Fig. 3 to 6 show further embodiments of the rolling bearing according to the invention. The representations in these figures have elements that are analogous to the elements shown in Fig. 1 and 2 or have analogous functions. The reference numerals of these elements are increased by 100, 200, 300 and 400 respectively compared to the reference numerals they have in Fig. 1 and 2.

In the following, only the differences between Fig. 1 and 2 on the one hand and the individual figures 3 to 6 on the other hand are described.

The two rolling bearings 101 and 201 shown in Fig. 3 and 4 each have two rolling tracks 106, 107, 241, 242 for two rows of rolling elements 109, 110 and

243, 244. The passages 116, 216 in this case open between the two rolling tracks of the rolling bearing in question. Fig. 3 shows a rolling bearing with two rows of rollers, while the rolling elements of the rolling bearing of Fig. 4 consist of a row of rollers 243 and a row of balls 244.

The rolling bearings 301 and 401 shown in Fig. 5 and 6 respectively have only a single rolling track on which the rolling elements are arranged (crosswise arranged rollers 329 and 330 in Fig. 5 and balls 450 with four contact points 451 in Fig. 6). In this case, the relevant passages 316 and 416 open approximately in the area of the axis of symmetry 331, 431 of the rolling track.

These different embodiments show that it is possible to provide the passages in one or the other of the two rings of the rolling bearing. It would also be possible to arrange the passages in both rings. Although all the previous figures show passages lying in the plane of the axial sections in question, it is particularly advantageous to provide several through holes formed in at least one of the two rings, distributed at selected points on the circumference of the ring or rings in question and each associated with a corresponding number of removable hollow elements. For example, it is possible to provide holes spaced 90° apart and arranged alternately with the lubrication holes.

Such an arrangement allows the removal of grease from different points on the rolling track. This allows an analysis to be carried out at different points in order to take into account, for example, uneven wear conditions caused by preferred alignment positions of the rolling bearing.

Claims (7)

MITSCHERLICH & PARTNER PATENT ATTORNEYS EUROPEAN PATENT ATTORNEYS Dipl.-Ing. H. Mitscherlich Dipl.-Ing. K. Gunschmann!«»»«&ogr;&igr; Dipl.-Ing. Dr.rer.nat. W. Körber Dipl.-Ing. J. Schmidt-Evers Dipl.-Ing. W. Melzer JJKS . „ Dipl.-Phys. Dr.rer.nat. R. Schulz Route de Vassy _also lawyer F-89200 AVALLON LAWYER France _ . _xt . _n . Dr. jur. Markus Graf 10 August 1993
Dr.Kö/Es/mpw Expectations 1. Rolling bearing, in particular directional rolling bearing, with two rings (2, 3, 4) which can be rotated relative to one another with the aid of rolling elements (9, 10, 13) which are arranged in a bearing gap (5) formed between the two rings and containing a lubricating grease substance, characterized by at least one passage (16) which opens directly into the middle of a predetermined area at the level of the bearing gap (5) and through which passage (16) lubricating grease substance can be removed for the purpose of its analysis. 2. Directional rolling bearing according to claim 1, characterized in that passages (16) are provided at various selected locations. 3. Rolling bearing, in particular directional rolling bearing according to claim 1, with two rings (2, 3, 4) which are rotatable relative to one another by means of rolling elements (9, 10, 13) which are arranged in a bearing gap (5) provided between the two rings, which contains a lubricating grease substance, characterized in that the at least one passage (16) is formed in one of the two rings and a hollow element (21) which is removably inserted into this passage (16) and has a front insertion opening (22) which is located inside the said passage (16) at a predetermined distance (D) from the end (23) of this passage (16) which opens into the bearing gap (5), the hollow element (21) being able to store part of the lubricating grease substance during the movement of the rolling elements. Postal address: Office address: Telephone (0S9) 5 22 &Zgr;&Iacgr; -0 Accounts for official fees: PO Box 33 06 09 Sonnenstraße 33 Fax (0X9) 5 5(1 24 35 Postbank Munich, Account 195 75-803 (Bank Code 700 100 80) D-80066 Munich D-80331 Munich Telex 5 23 !55 niitsh d EPA-Kto. 28 000 206 4. Rolling bearing according to claim 3, characterized in that the said distance (D) is selected to be smaller than or equal to the inner diameter of the passage (16). 5. Rolling bearing according to claim 3 or 4, characterized in that the region of the ring in which the passage (16) is formed is a region of minimal mechanical stresses. 6. Rolling bearing according to one of claims 3 to 5, characterized in that the hollow element (21) is made of a non-metallic material and a hollow tube ¹ ^ (23) which can receive the lubricating grease substance through the said frontal introduction opening (22) and has at its other end an end wall (26) which is connected to the outside of the hollow element (21) via a narrow passage (27). ^ 5 7. Rolling bearing according to one of claims 3 to 6, characterized in that it has two rolling tracks (106, 107, 241, 242) for two rows of rolling elements (109, 110, 241, 242) and that the passage (365, 416) opens between the two rolling tracks. 8. Rolling bearing according to one of claims 3 to 6, characterized in that it has a single rolling track and that the passage (365, 416) opens approximately in the region of the axis of symmetry (331, 431) of the rolling track. 9. Rolling bearing according to one of claims 3 to 6, characterized in that it has three rolling tracks (6, 7, 8), namely an upper rolling track (6), a lower rolling track (7) and a central rolling track (8) located between them and that at least two passages (16, 17) are provided which open at the level of the upper (6) or the lower rolling track (7). 10. Rolling bearing according to one of claims 3 to 9, characterized in that the rolling bearing is a directional rolling bearing and has a plurality of passages which are formed in at least one of the rings and to which a corresponding number of removable hollow elements are associated, and which are arranged at selected Places are distributed around the circumference of the ring or rings. 35